Summary

Symptomless seed tubers are no guarantee for them being free of tuber blight, therefore they bear the risk of bringing P. infestans to the fields. Because of the high risk of using infected seed tubers control measures are highly recommended. Systemic fungicides spread into the plant tissue and can reduce the growth of the fungus from within the plant. Treating seed tubers with copper is another possibility especially in organic farming. Further research should deal with possibilities to reduce latent infections of seed tubers with P. infestans as they are the main reason for an early outbreak and a strong late blight epidemic.